31 minutes ago, Compound2632 said:

 "where one of the buffer holes cracked out when I was drilling it out for the buffers, leaving a big hole in the bufferbeam. I swapped to a needle file to do the rest after this!"

 

Been there, done that. I described it as a knack but was firmly put in my place - it's a bodge. The correct procedure, I was told, is to run the drill bit counter-clockwise. I subsequently did this (installing cast buffers on the second of your Brighton Open As) and it works.

 

I found the needle file in a small power drill worked well run in reverse, with the added benefit that it was easy to move the hole a little bit if it started to wander from the centre. I think the maximum drill size for this sort of material is about 1.5mm, and even then it's a bit risky. Lessons learned and fortunately not too much harm done!